Power converters provide an adjustable voltage and frequency to an output through a Pulse Width Modulated (PWM) voltage source inverter drive. A typical power converter is a switching apparatus having two or more power semiconductor devices such as power semiconductor switches which can be abbreviated as power switches. A power switch can, for example, be implemented by an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET).
Power converters can be used in an uninterruptible power supply (UPS) system, electric motors, etc. A PWM signal is used in the power converter for controlling power to inertial electrical devices. A duty cycle of a power switch (ratio of on-time to total cycle time) is varied to achieve a desired average output voltage, current etc., when averaged over time.
A large UPS system may use a centralized core controller. FIG. 7 shows a schematic diagram of a conventional system for use in a power converter such as a UPS system. PWM signals such as IGBT switch commands are distributed through individual wires 821-829 from the controller 800 to a number of power switches 191-199. These individual wires 821-829 are often grouped together as ribbon cables. To drive a power converter, it is necessary to send switch command signals to a driver board through an individual wire.
The number of switch commands in a UPS system may increase in future. The increased number of PWM signals, combined with the length of the wires, brings a challenge to the reliability of a power converter such as a UPS system, as the reliability of an electronic system is often linked to the number of connector pins, and the reliability of a UPS system will decline with the increase of the number of connector pins and wires. Switch commands are fast and critical signals, which are sensitive to noise over the length of a wire. The increase of the number of wires also makes the cost of cables and connector pins high and occupies more space within a UPS system.